1. Field of the Invention
This invention relates generally to the testing of hydraulic/pneumatic apparatus and more specifically to an apparatus and a method for testing such apparatus utilizing computer controlled automatic test equipment.
2. Prior art
It has been common practice in the art to test hydraulic/pneumatic component subsystems and systems (devices) subsequent to their assembly to ascertain whether such devices are operating in accordance with the specifications set forth for them. Such testing may occur at the time of manufacture of the device or subsequently during maintenance thereof. For example, it is typical to connect a hydraulic actuator to a test stand and determine its frequency response, external and internal leakage, proof pressure, ram travel and velocity, damping, hysteresis and the like.
In such prior art test stands, the device may be connected to dedicated ports for application of fluid under pressure and/or return thereto, or alternatively, connected arbitrarily to ports which can then be controlled by a computer through a manifold so that the desired pressure and return is then applied to the ports to which the device has been connected. One example of such a structure is that shown and described in U.S. Pat. No. 4,480,464, which is incorporated herein by reference. Subsequent to connection of the device, the system steps through a series of tests to ascertain whether or not the device is functioning according to its predetermined specifications. The tests may be performed in accordance with selections made by an operator's input or alternatively, in a manner controlled automatically by a computer controlled system. Examples of such computer controlled automatic testing systems are as shown and described in U.S. Pat. No. 4,782,292, which is incorporated herein by reference. In such systems, a computer control system automatically sequences through a plurality of tests specific to the device being tested, determines whether the device falls within the predetermined tolerances programmed within the system and thus, whether it has met the predetermined specifications or not.
A similar automatic testing structure is that as shown and described in U.S. Pat. No. 4,916,641 which is incorporated herein by reference. Such a system receives and stores a plurality of tables of data. Each such table contains data which is characteristic to the specific device being tested. Additional tables of data are also stored with each such additional table containing data which is characteristic of each transducer, amplifier or other component relating to the device to be tested. The table of characteristic data for each such transducer, amplifier or other component can then in effect be used by incorporating it into other definition tables. Thus for each such transducer, amplifier or other component there is developed a specific set of characteristic data which is then automatically referenced or used when desired and as controlled by the computer control system to test a particular device. Thus, when a specific device to be tested is identified, the computer will search out the tables containing the set of data characteristic to the device, to the transducers, the amplifiers and the other components as they use those data to test the device.
Although the prior art systems have worked quite well for the applications intended, it is evident that if there is any change in the hardware, either in the test stand or the device, then each of the tables of characteristic data must be changed to accommodate the same. Those skilled in the art will recognize that such changes can effect the overall operation of the system in that they must be incorporated into a plurality of different tables of characteristic data resulting in necessary changes in the system software. Such changes necessarily add to the expense for maintenance and operation of the system as well as introducing problems of reliability.